Cell Type–specific labeling using Amino acid Precursors (CTAP) is an approach
for introducing stable-isotope labeled amino acids into the proteome of distinct
cell types in multicellular culture. In short, transgenic expression of exogenous
amino acid biosynthesis enzymes allows vertebrate cells to overcome their
dependence on supplemented essential amino acids through supplementation of
precursors to these amino acids. These transgenic cells can be selectively labeled
through metabolic incorporation of amino acids produced from heavy
isotope–labeled precursors. In coculture, expression of distinct amino acid
biosynthesis enzymes in each cell type enables continuous cell-selective proteome
labeling using differentially labeled precursors. Quantitative mass spectrometry–based
analysis of coculture samples can then be used to determine relative abundance of proteins
from each cell type.

The CTAP methodology was validated with the essential amino acid
l-lysine and a manuscript
describing the method can be downloaded directly from the publishers website:

This page contains the CTAP.ms Google Groups Forum. For a direct link to
the google groups page, click here

This page contains links to raw LC-MS/MS data for Gauthier
et al (2013).
For MaxQuant processed versions of these same data, which include the identified peptides/proteins
as well as intensity and H/L ratios for each figure, please see the Supplementary Data File
on the publishers website here.
Other raw data for the manuscript is available through the following:

Schematics of the vector inserts used in this study can be found in the
Supplementary Information File here.

★: This sample contained mixed monocultures of heavy-labeled 3T3 cells and unlabeled MDA-MB-231 cells.
As described in Note 1 below, the figure in the manuscript was filtered for mouse specific peptides (i.e., all peptides existing in the human
proteome IPI database were removed).

★★: Processed with MaxQuant version 1.3.0.5. Note that all other data were processed with MaxQuant version 1.2.2.5.

Note 1: All peptide data were filtered for species-specific peptides, regardless of whether cells were mono- or cocultured.